Integrated Cold Plate TXV for Uniform Multi-Source Cooling
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Solution Overview
Problem
Vapor compression cooling systems face challenges in achieving uniform temperature distribution across multiple discrete heat sources due to high fluid velocity and pressure loss, leading to component failure and increased complexity in plumbing and control systems.
Innovation Solution
Integrating compact thermostatic expansion devices (TXVs) directly into each cold plate, allowing for localized control of refrigerant flow and temperature uniformity, eliminating the need for external distributors and capillary tubes, and enabling field replacement without brazing or soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external distributors with discrete orifices are used to supply cooling to multiple discrete heat loads, then flow distribution between conduits is near uniform, but pressure loss is considerable and plumbing complexity increases dramatically
Solution Approach 1:
The system divides the cooling load into multiple independent cold plate modules, each with its own integrated TXV. This segmentation allows each module to be controlled independently while simplifying the overall plumbing architecture, as each cold plate is a self-contained unit requiring minimal external piping.
Solution Approach 2:
The TXV and cold plate are merged into a single integrated assembly. The expansion device is built directly into each cold plate, eliminating the need for separate external distributors and complex two-phase plumbing. This merging reduces the number of components and connections while maintaining uniform flow distribution.
2Manufacturing precision
If high fluid velocity is used through discrete orifices in external distributors, then flow distribution is momentum-driven and near uniform, but pressure loss is considerable
Solution Approach 1:
The TXV performs preliminary expansion and regulation of refrigerant flow before it enters the cold plate evaporator. By controlling the expansion process upstream at each individual cold plate, the system achieves uniform flow distribution without requiring high velocity through restrictive orifices, thereby reducing pressure losses.
Solution Approach 2:
Each cold plate with its integrated TXV is a self-regulating unit that automatically adjusts its own refrigerant flow based on local thermal conditions. This self-service capability eliminates the need for high-velocity momentum-driven flow distribution from a central distributor, as each unit serves itself with appropriately controlled flow rates.
3Power
If the number of discrete cold plates increases, then cooling capacity increases, but the size, weight, and complexity of plumbing increases dramatically
Solution Approach 1:
The system is segmented into multiple independent cold plate modules, each functioning as a self-contained cooling unit with integrated TXV. This modular architecture allows scaling of cooling capacity by simply adding or removing modules without proportionally increasing plumbing complexity, as each module requires minimal external piping.
Solution Approach 2:
By merging the TXV and cold plate into a single integrated assembly, the system eliminates the need for complex external two-phase plumbing that would otherwise be required to serve multiple discrete cold plates. This merging dramatically reduces the size, weight, and complexity of the overall plumbing system while maintaining the ability to scale cooling capacity.
4Ease of operation
If conventional TXV with external sensing bulb and capillary tube is used, then refrigerant flow is controlled, but response time is slow due to reliance on conduction
Solution Approach 1:
The sensing element and TXV are merged into a single integrated assembly located within the cold plate. The sensing element is positioned in direct thermal contact with the cold plate surface, eliminating the need for external capillary tubes and long conduction paths. This merging enables rapid detection of temperature changes and quick adjustment of refrigerant flow, achieving response times of less than 400 milliseconds.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the cooling system, reduces complexity and weight, enhances temperature uniformity to 2°C, and achieves rapid response times of less than 400 milliseconds, suitable for advanced electronics and high-power lasers.
Implementation Method 1
the action of the integral TXV (of the cold plate) via opening or closing an internal orifice controls the flow to each cold plate
Implementation Method 2
Integrating the sensing element with the TXV eliminates the capillary tube used in conventional TXV systems and improves the time response of the TXV because the sensing element can be immersed in the exiting refrigerant stream
Implementation Method 3
supplying cooling to discrete sources (or circuits in an evaporator)
Implementation Method 4
vapor-compression cooling that can supply heat transfer coefficients up to 100,000 W/m2K
Data Source
AI summary
A flow control cartridge is used with a cold plate to form a cold plate assembly within which a refrigerant circulates for cooling at least one heat generating device. The cartridge includes a thermal expansion valve and a sensing portion that with a bellows-type actuator within the cartridge. The bellows-type actuator is located directly in a stream of the refrigerant exiting the cold plate. The thermal expansion valve is comprised of a main body having an inlet orifice arranged to receive refrigerant that has been subcooled from a condenser of a vapor compression system or a recuperative heat exchanger, and a needle arranged in an expanded section of the main body in association with discharge ports in the expanded section for discharging the refrigerant in a two-phase state into the cold plate.